What to do about my neighbor?

Carlos is my neighbor. He was a quiet man, tending to his lemon trees in the afternoons. Nowadays he seems to be a troublemaker. He let his cattle get out of their pen to graze in the nearby field (that he did not own) and they all paraded to my yard, trampling my flowers and eating my vegetables. Last night I was reading a novel in my study sipping my exotic garden tea, which was very tasty, I must say, and thought of trolling Yahoo Answers, which is what I'm doing right now.